The present invention relates to one component, alkoxy functional room temperature vulcanizable (RTV) compositions. More particularly, the present invention relates to isocyanate functional organic compounds which are effective as scavengers for chemically combined hydroxy groups in one component, alkoxy functional silicone RTV compositions.
Recently a shelf-stable, fast-curing, one component, alkoxy functional RTV composition was disclosed in the patent of White et al., U.S. Pat. No. 4,395,526, and assigned to the same assignee as the present invention. Basically White et al. disclose that moisture curable, polyalkoxy terminated organopolysiloxane RTV compositions can be made by combining:
(1) a silanol terminated polydiorganosiloxane base polymer, PA1 (2) a crosslinking silane, PA1 (3) an effective amount of certain silane scavengers for chemically combined hydroxy radicals such as methanol, and PA1 (4) an effective amount of a condensation catalyst. PA1 (A) a polydiorganosiloxane base polymer wherein the silicon atom at each chain end is terminated with at least two alkoxy radicals; PA1 (B) an effective amount of condensation catalyst; and PA1 (C) a stabilizing amount of organic scavenger for hydroxy groups having the formula: EQU R--N.dbd.C.dbd.O).sub.x PA1 (A) a polydiorganosiloxane base polymer wherein the silicon atom at each chain end is terminated with at least two alkoxy radicals; PA1 (B) an effective amount of condensation catalyst; and PA1 (C) a stabilizing amount of organic scavenger for hydroxy groups having the formula: EQU R--N.dbd.C.dbd.O).sub.x PA1 (A) a silanol terminated polydiorganosiloxane base polymer; PA1 (B) an effective amount of condensation catalyst; PA1 (C) a stabilizing amount of organic scavenger for hydroxy groups having the formula: EQU R--N.dbd.C.dbd.O).sub.x PA1 (D) an effective amount of a crosslinking silane of the formula: ##STR1## where R.sup.1 is a C.sub.(1-8) aliphatic organic radical selected from the group consisting of alkyl, alkylether, alkylester, alkylketone and alkylcyano or a C.sub.(7-13) aralkyl radical; R.sup.2 is a C.sub.(1-13) monovalent substituted or unsubstituted hydrocarbon radical; and e equals 0 or 1; and PA1 (E) optionally, an effective amount of a co-catalyst or curing accelerator selected from the group consisting of substituted guanidines, amines and mixtures thereof.
The scavenger, which can be either a separate compound or part of the crosslinking silane, has a functionality selected from the group consisting of amido, amino, carbamato, enoxy, imidato, isocyanato, oximato, thioisocyanato and ureido. The disclosure of White et al. is incorporated by reference into the present application.
Shortly after the pioneering invention of White et al. it was discovered that compounds other than those disclosed by White et al. could be utilized as scavengers for chemically combined hydroxy groups or as integrated scavenger-cross-linkers. For example, Dziark, U.S. Pat. No. 4,417,042, discloses silazanes and silyl-nitrogen polymers as scavenger compounds; Lucas, Ser. No. 464,443, filed Feb. 7, 1983, discloses novel acetamide functional silane and siloxanes as scavengers; Chung et al., Ser. No. 428,038 filed Sept. 29, 1982, discloses additional silazane scavengers; Chung, Ser. No. 338,518, filed Jan. 11, 1982, now U.S. Pat. No. 4,424,157, discloses silanes having cyclic amide functionality as scavenger compounds; Mitchell, Ser. No. 462,949, filed Feb. 1, 1983, discloses additional amine functional silanes and siloxanes which are effective scavengers and Swiger et al., Ser. No. 476,000, filed Mar. 17, 1983, discloses additional silane and siloxane scavengers. All of the foregoing patent applications are assigned to the same assignee as the present invention and are incorporated by reference into the instant disclosure.
In each of the above cited patent applications it was essential that the scavenger compound include silicon atoms, for example, as silanes, siloxanes or silazanes. Thus, it was quite unexpected that non-silicone compositions could be utilized as hydroxy scavenging agents so as to provide silicone RTV compositions which exhibit excellent shelf stability.
It is therefore an object of the present invention to provide novel hydroxy scavenging agents for use in polyalkoxy-terminated polysiloxane RTV compositions to obtain improved shelf stability.
It is another object of the present invention to provide a method for producing silicone RTV compositions which include the novel hydroxy scavenging agents of the present invention.
Other objects and advantages of the present invention will be obvious from the following detailed description.